Without limiting the scope of the present invention, its background is described with reference to the production of hydrocarbons through a wellbore traversing an unconsolidated or loosely consolidated formation, as an example.
It is well known in the subterranean well drilling and completion art that particulate materials such as sand may be produced during the production of hydrocarbons from a well traversing an unconsolidated or loosely consolidated subterranean formation. Numerous problems may occur as a result of the production of such particulate. For example, the particulate causes abrasive wear to components within the well, such as tubing, pumps and valves. In addition, the particulate may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids by processing equipment at the surface.
One method for preventing the production of such particulate material to the surface is gravel packing the well adjacent the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a completion string including a packer, a circulation valve, a fluid loss control device and one or more sand control screens is lowered into the wellbore to a position proximate the desired production interval. A service tool is then positioned within the completion string and a fluid slurry including a liquid carrier and a particulate material known as gravel is then pumped through the circulation valve into the well annulus formed between the sand control screens and the perforated well casing or open hole production zone.
The liquid carrier either flows into the formation or returns to the surface by flowing through the sand control screens or both. In either case, the gravel is deposited around the sand control screens to form a gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the particulate carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of particulate materials from the formation.
During such a gravel packing operation, the service tool used to deliver the gravel slurry must be operated between various positions. For example, the service tool typically has a run-in configuration, a gravel slurry pumping configuration and a reverse out configuration. In order to operate the service tool between these positions, the service tool is typically moved axially relative to the completion string. In addition, the service tool is typically used to open and close the circulation valve, which also requires the axially movement of the service tool relative to the completion string.
It has been found, however, that such axially movement of the service tool relative to the completion string can adversely affect the formation. Specifically, movement of the service tool uphole relative to the completion string can undesirably draw production fluids out of the formation. Likewise, movement of the service tool downhole relative to the completion string can undesirably force wellbore fluids into the formation. This type of swabbing can damage the formation including, for example, damaging the filter cake in an open hole completion. Therefore a need has arisen for a service tool that is able to be operated between its various positions without swabbing the formation.